Armored lock mechanism

ABSTRACT

A protective housing is locked onto the fifth-wheel king pin of a tractor-trailer connection to prevent its being engaged by an unauthorized tractor. A housing ring closely encircles the king pin and carries a projecting lock body housing a cylindrical latch bolt spring pressed into engagement with the king pin groove. The latch bolt is rotated to release position by a keyactuated lock cylinder having its key-entrance face presented at the front face of the lock body. An armor shield having a lockinsertion opening is welded in spaced relation to that face to define a slot to receive a guard plate which is inserted across the lock-insertion opening after a lock cylinder and core have been inserted. The guard plate carries a rotatable, key-slotted disk in an opening coaxial with the key plug of the lock, which protects the key plug from drilling and from forceful withdrawal by a pulling tool. The guard plate is removably locked in place by a ball in a hole across the body-plate interface, held therein by a dowel and set screw in a hole which opens to the end face of the lock body and is concealed by the fifth wheel bearing pad on the trailer when the locking device is in place.

United States Patent McCullum Mar. 26, 1974 ARMORED LOCK MECHANISM [75] Inventor: R. Gene McCullum, Indianapolis,

Ind.

[73] Assignee: Best Lock Corporation,

Indianapolis, Ind.

[22] Filed: Mar. 2, 1973 [21] Appl. No.: 337,755

Primary Examiner-Albert G. Craig, Jr. Attorney, Agent, or FirmTrask, Jenkins & Hanley [57] ABSTRACT A protective housing is locked onto the fifth-wheel king pin of a tractor-trailer connection to prevent its being engaged by an unauthorized tractor. A housing ring closely encircles the king pin and carries a projecting lock body housing a cylindrical latch bolt spring pressed into engagement with the king pin groove. The latch bolt is rotated to release position by a key-actuated lock cylinder having its key-entrance face presented at the front face of the lock body. An armor shield having a lock-insertion opening is welded in spaced relation to that face to define a slot to receive a guard plate which is inserted across the lockinsertion opening after a lock cylinder and core have been inserted. The guard plate carries a rotatable, key-slotted disk in an opening coaxial with the key plug of the lock, which protects the key plug from drilling and from forceful withdrawal by a pulling tool. The guard plate is removably locked in place by a ball in a hole across the body-plate interface, held therein by a dowel and set screw in a hole which opens to the end face of the lock body and is concealed by the fifth wheel bearing pad on the trailer when the locking device is in place.

6 Claims, 5 Drawing Figures -21 24 80 Q I 41 I 7e as 0 1 1 38 111 L4: l1 ,3:

\/\\\\1\l\\ 1 '\68 l l I ll 1 1 k I vk IS a L 32 34 13is4428 ARMORED LOCK MECHANISM BACKGROUND OF THE INVENTION The present invention relates particularly to king-pin locks, but is applicable to other similar locking situations. King pin locks of the type here involved have been previously known in which the faces of the lock cylinder and its core (if any) and its key plug have been openly exposed. Such locks have been forced by engaging a pulling tool in the key plug and forcibly retracting the plug or the core and then inserting a tool to withdraw the lock bolt. The present invention obstructs this forced entry by providing a protective armor shield and guard plate across in front of the lock cylinder and core, and a slotted guard disk in front of the key plug which permits insertion of the key but obstructs entry of a pulling tool and withdrawal of the key plug. It also guards against drilling. The protective armor provides for insertion of the cylinder and for removal and replacement of the preferred lock core, by using a separate guard plate which is removable only by access through that face of the device which lies against the bearing pad of the king pin assembly, and hence not removable when the lock is in locked position.

A king-pin lock in accordance with the invention comprises a cylindrical housing which fits about the king pin and which carries a lock body containing a slidable and rotatable latch bolt controlled by a keyoperated pin tumbler lock mounted in the lock body through an opening in its front face. In the locking position of the body its front face is exposed for key access, and its upper end face, at an angle to said front face, lies against the opposing surface of the fifth wheel pad, which obstructs access thereto. The body contains a lock chamber opening through the front face for the reception of a lock mechanism containing a keyrotatable key plug. An armorshield is integrally fixed to the lock body in spaced overlying relation with its front face and defines therewith a slot for the reception of a guard plate, with a guard-plate insertion opening at the end face. The shield has a face opening in registry with the lock chamber for passing the lock mechanism to the chamber. A guard plate is inserted in the slot through the insertion opening to a protective position in which it extends across the face opening in the shield.

The guard plate has a key-access opening aligned with the key plug of the lock mechanism, and a guard disk is rotatably mounted in such key access opening and contains a restricted key slot to pass a key to the key plug of said lock mechanism and to rotate therewith as the key is turned. A guard plate retainer, such as a ball, is insertedin an opening through said end face to a passage crossing the body-plate interface, where it engages the guard plate to block its removal from its protective position in the slot. When the lock is in place on a king pin, the opposing surface of the king-pin bearing pad obstructs access to the retainer passage and the guard-receiving slot to prevent removal of the guard plate from behind the armor shield. The invention may also be used in other applications where a similar locking device has one face which is inaccessible when the device is in locked position.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention. In such drawings:

FIG. I is a top elevation of a king pin locking device embodying this invention;

FIG. 2 is a longitudinal section on the line 22 of FIG. 2;

FIG. 3 is an end elevation of the device of FIG. 1;

FIG. 4 is a section on the line 4-4 of FIG. 2; and

FIG. 5 is an isometric'view of a key-removable lock core containing the pin tumbler lock.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The locking device shown in the drawings is adapted to prevent engagement by an unauthorized tractor of the king pin 10 of the fifth-wheel connection of a trailer, so as to prevent the trailer from being hitched to the unauthorized tractor and stolen. The king pin 10 projects downward from a bearing pad 12 on the trailer and is provided with a locking groove 14 by which it is locked to the fifth wheel plate on the tractor. The locking device shown comprises a housing ring 16 adapted to closely encircle the king pin 10 and to be held thereon by a latch bolt 18. The latch bolt 18 is mounted in a lock body 20 which projects radially from the housing ring with its upper face 22 flush with the upper edge of the housing ring 16 so that when the locking device in in place, such upper face 22 lies against the bearing pad 12.

The latch bolt 18 is slidable and rotatable in a bore 24 in lock body 20. Such bore connects to a lock chamber 26 which receives a lock cylinder 28. The latch bolt 18 has a sloping cam face 30 which is normally disposed upward to retract the bolt when the ring is moved upward over the king pin 10. The bolt is urged toward protected position by a spring 32 disposed about a reduced stem portion 34 of the bolt and acting between a shoulder on the bolt and a retaining plate 36 secured in the bottom of the chamber 26 by two cap screws 38. Forward movement of the bolt 18 is limited by a retainer ring 40 mounted in a groove at the rear of the reduced portion 38, behind the plate 36. The stem 34 of the bolt is provided with a diametric slot 42, shown in FIG. 4, for the reception of a flattened rear end of a throw member 44 rotatably mounted in the rear wall of the lock cylinder 28. A pair of spaced legs 46 project forward from the throw'member 44 for engagement in matching holes in the rear of the key plug 48 of the core 50 in the cylinder.

The pin tumbler locking mechanism is desirably contained in a key-removable core as shown in FIG. 5. This comprises a body 50 of figure-8 cross section containing the key plug 48 in its lower lobe and containing tumbler pins in its upper lobe. It is of a type shown in US. Pat. No. 3,206,959, and has a locking cam 52, retractable by means of a special key in the key plug 48, which is adapted to engage over a shoulder in the cylinder 28 to retain the core 50 in place in the cylinder. The cylinder 28 is held in place by a drive pin 56 inserted in the reduced lower end of a bore through the top face 22 of the lock body.

The lock chamber 26 opens through the front face of the lock body 20, for insertion of the lock cylinder 28, and for insertion and removal and replacement of the core 50. When the core is in place, the key entrance end of the key plug 48 lies substantially flush with the front face of the body.

To protect the cylinder and core and key plug from drilling and pulling, the front end of the lock body 20 carries an armor shield 60 which has side legs 62 and a bottom leg 64 welded to the sides and bottom of the body 20. The shield also has a front wall 66 which is disposed in spaced relation with the front face 21 of the body 20 to define therewith a vertical slot closed at its sides and bottom and open at the top. The front shield wall 66 contains a face opening 68 in registry with the lock chamber for passing the lock cylinder 28 into the chamber 26 and to permit insertion and removal of the core 50. To close this face opening after the cylinder and core are inserted, a guard plate 70 is slidably inserted into the slot, from above. lt substantially fills the slot, and extends across the face opening 68, in front of the lock mechanism. For key access to the key plug, the guard plate 70 contains a key insertion opening 72 aligned with the key plug 48. A guard disk 74 is rotatably mounted in a counter bore in the back face of the guard plate 70, and contains a restricted key slot 76. The guard disk 74 is large enough so that it edges overlap the cylinder edges defining the core cavity in the cylinder 28 and the disk is supported from behind by the front face of the cylinder 28 and core 50 and lies behind the inner periphery of the guard plate 70 about the counterbore.

The guard plate 70 is held in place by a retaining ball 78 positioned in across hole 80 having a rear portion drilled in'the front face of the body 20 and a front portion drilled partway through the plate 70. The ball 78 lies across the interface between the lock body 20 and the guard plate 70. A blind hole 82 drilled downward through the top face of the body 20 and across the hole 80 permits insertion of the ball 78, and contains a dowel 84 and set screw 86 by which the ball 78 is held in locking position across the interface.

Assembly is as follows: With the guard plate 70 removed from the slot, a subassembly of a bolt 18, spring 32, mounting plate 36 andretaining ring 40 is inserted through the face opening 68 and the lock chamber 26, and is secured in place with the cap screws 38. A lock cylinder 28 is then inserted through the face opening 68 and secured in place with a drive pin 56. A core 50 is then inserted in the core cavity of the cylinder 28 and the holes at the rear of the key plug 48 are engaged with the throw member legs 46. The lug 52 is projected from the core body by turning the control key to engage that lug behind the shoulder 54 in the core cavity, and the control key is then withdrawn. A guard plate 70 is then inserted in the slot from the top, with a guard disk 74 in place in its rear eounterbore. A ball 78 is then dropped in the hole 82 and moved forward into the cross passage 80, and a dowel 84 is dropped in behind it and secured with a set screw 86. The top end of the hole 82 may be filled with lead or other packing if desired.

Operation of the locking device is as follows: The lock bolt 18 is normally in the position shown, with its cam face 30 presented upward. The locking ring is installed by upward movement over the king pin 10, and this causes the bolt 18 to retract resiliently against the spring 32 until its nose snaps into the locking groove 14 of the king pin. The ring is then locked in place and cannot be removed except by key operation. For such removal, an operating key is inserted through the key slot 72 of the guard disk 74 into the key plug 28, and rotated 180. This rotates the throw member 44, which in turn rotates the bolt 18 through 180. This disposes the cam face 30 downward, so that it will cam the bolt to retracted position when the housing ring is pulled downward off the king pin 10.

The shield 60, the guard plate and the guard disk 74 are all made of hardened steel or other hard and strong material which resists cutting and drilling, so that those parts in the assembly protect the lock mechanism against attack either from the front or from the sides or bottom. The restricted key slot in the guard disk, and its freely rotatable mounting, obstruct drilling. These also obstruct insertion of pulling tools into the key plug 48, and block forceful retraction of that plug by any such tools.

The lock core 50 may be removed and replaced if desired. To this end, the set screw 86, dowel 84, and block ball 78 can all be removed, and this will permit removal of the guard plate 70 from the slot so that the face of the cylinder is exposed and the core 50 can be removed by means of a control key in the usual manner.

I claim:

1. An armored locking device, comprising a lock body adapted to be locked in a locking position and having a front face which in such position of the body is exposed for key access, and having an end face at an angle to said front face and which in such position of the body lies against an opposing surface which obstructs access thereto,

a lock chamber opening through said front face for the reception of a lock mechanism containing a key-rotatable key plug,

an armor shield integrally fixed to said body in spaced overlying relation with said front face and defining therewith a slot for the reception of a guard plate and having a guard-plate insertion opening at said end face, said shield having a face opening in registry with said lock chamber for passing the lock mechanism to said chamber,

a guard plate for insertion in said slot through said insertion opening to a protective position in which it extends across said face opening,

said guard platehaving a key-access opening aligned with the key plug of said lock mechanism,

a guard disk rotatably mounted in said key access opening and containing a restricted key slot to pass a key to the key plug of said lock mechanism and to rotate therewith as the key is turned, and

a passage in said lock body, opening through said end face, for the reception of a guard plate retainer, and a guard plate retainer in said passage and engaging said guard plate to block removal thereof from said protective position,

said opposing surface obstructing access to said retainer passage and said guard-receiving slot when the lock body is in said locked position to prevent removal of the guard plate.

2. A locking device'as in claim 1 with the addition that such lock mechanism includes a key-removable lock core.

3. A locking device as in claim 1 in which said guard plate retainer comprises a blocking element extending across the interface between the lock body and the guard plate.

4. A locking device as in claim 3 in which the blocking element is disposed in a cross-hole from behind, said body contains a blind hole communicating with said cross hole and having its open end at said end face,

the plug and blocking element are removable to permit removal of the guard plate for access to and removal of the key-removable lock core.

6. A locking device as in claim 2 in which the cross hole is normal to the guard plate and extends only part way therethrough from behind, and the blind hole is normal to said body end face and at right angles to the cross hole. 

1. An armored locking device, comprising a lock body adapted to be locked in a locking position and having a front face which in such position of the body is exposed for key access, and having an end face at an angle to said front face and which in such position of the body lies against an opposing surface which obstructs access thereto, a lock chamber opening through said front face for the reception of a lock mechanism containing a key-rotatable key plug, an armor shield integrally fixed to said body in spaced overlying relation with said front face and defining therewith a slot for the reception of a guard plate and having a guardplate insertion opening at said end face, said shield having a face opening in registry with said lock chamber for passing the lock mechanism to said chamber, a guard plate for insertion in said slot through said insertion opening to a protective position in which it extends across said face opening, said guard plate having a key-access opening aligned with the key plug of said lock mechanism, a guard disk rotatably mounted in said key access opening and containing a restricted key slot to pass a key to the key plug of said lock mechanism and to rotate therewith as the key is turned, and a passage in said lock body, opening through said end face, for the reception of a guard plate retainer, and a guard plate retainer in said passage and engaging said guard plate to block removal thereof from said protective position, said opposing surface obstructing access to said retainer passage and said guard-receiving slot when the lock body is in said locked position to prevent removal of the guard plate.
 2. A locking device as in claim 1 with the addition that such lock mechanism includes a key-removable lock core.
 3. A locking device as in claim 1 in which said guard plate retainer comprises a blocking element extending across the interface between the lock body and the guard plate.
 4. A locking device as in claim 3 in which the blocking element is disposed in a cross-hole from behind, said body contains a blind hole communicating with said cross hole and having its open end at said end face, and such element is retained in the cross hole by a removable plug in the blind hole.
 5. A locking device as in claim 2 in which the guard plate retainer comprises a blocking element mounted in a cross hole across the interface between the lock body and guard plate, said body contains a blind hole communicating with the cross hole and having its open end at said body end face, said blocking element is retained in the cross hole by a plug in the blind hole, and the plug and blocking element are removable to permit removal of the guard plate for access to and removal of the key-removable lock core.
 6. A locking device as in claim 2 in which the cross hole is normal to the guard plate and extends only part way therethrough from behind, and the blind hole is normal to saiD body end face and at right angles to the cross hole. 